Cygwin Rsync/SSH performance issue

[Jan Alphenaar]

Hi again,

I did some more testing on this and figured out that rsync/ssh is only
taking the full cpu if the bandwidth allocated to the session exceeds the
true bandwidth available on the link.

For example, if the uplink is 128KB/s and I pass in the --bwlimit=24
parameter the cpu is around 0%. Even --bw-limit=126 does not take 100% cpu,
but --bwlimit=132 does.

Would this be because of packet loss on the link and packets have to be
retransmitted ? I will do a quick test tonight with rsync/ssh between two
linux boxes, see what that gives me.

Regards,

Jan

-----Oorspronkelijk bericht-----
Van: Jan Alphenaar [mailto:jan.alphenaar@dotcolour.com] 
Verzonden: dinsdag 16 februari 2010 11:34
Aan: 'cygwin-developers@cygwin.com'
Onderwerp: Cygwin Rsync/SSH performance issue

Hi everybody,
 
I am using rsync/ssh to copy files from my computer to my server and
everything seems to function as expected, except performance.

During a file transfer on my home computer (Intel I7) there is not a
noticeable CPU load. But on other (older) machines the rsync/ssh transfer
consumes all CPU resources on the sending side. I noticed there are other
questions regarding this subject in the archives, but I could not find a
solution for this. Also throttling the bandwidth to a lower value is not
helping to reduce the CPU load.

I am using quite a basic command to sync my files:

        rsync -e ssh * <user>@<server>:/data

The versions of the software I am using are:

Cygwin: 1.7.1-1
ssh: OpenSSH_5.3p1
rsync: 3.0.6
OS: WinXP

Was anybody able to resolve this ?

Any help is greatly appreciated.

Warm regards,

Jan